Game 5 last year was as close to "being down" as a team could be, considering how 3 & 4 went.
Also, Spurs have "been down", dropping game 1 of series many times, only to come storming back. Typically the Spurs play from in front; taking control of series, and finishing teams off. Notable exception is Detroit last year; and conventional wisdom, all national pundits, and certainly Detroit Fan thought for SURE that that tough Detroit 7th game experience would rule the day.
Fact is, Detroit tightened, the Spurs extended; would HCA have made a difference? I don't know, and neither do you. All I know is, Detroit has made a big deal about that HCA all year, and has played their asses off to get it. How will they respond if the Spurs come in and pop em in the mouth in game 1, and wrench that hard-fought, absolutely essential, HCA away in 48 minutes? I'm betting not well.